Network Working Group M. Stapp
Request for Comments: 4703 B. Volz
Category: Standards Track Cisco Systems, Inc.
October 2006
Resolution of Fully Qualified Domain Name (FQDN) Conflicts
among Dynamic Host Configuration Protocol (DHCP) Clients
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
The Dynamic Host Configuration Protocol (DHCP) provides a mechanism
for host configuration that includes dynamic assignment of IP
addresses and fully qualified domain names. To maintain accurate
name-to-IP-address and IP-address-to-name mappings in the DNS, these
dynamically assigned addresses and fully qualified domain names
(FQDNs) require updates to the DNS. This document identifies
situations in which conflicts in the use of fully qualified domain
names may arise among DHCP clients and servers, and it describes a
strategy for the use of the DHCID DNS resource record (RR) in
resolving those conflicts.
Stapp & Volz Standards Track [Page 1]RFC 4703 Resolution of FQDN Conflicts October 2006Table of Contents
1. Introduction ....................................................3
2. Terminology .....................................................3
3. Issues with DNS Update in DHCP Environments .....................4
3.1. Client Misconfiguration ....................................4
3.2. Multiple DHCP Servers ......................................5
4. Use of the DHCID RR .............................................5
5. Procedures for Performing DNS Updates ...........................6
5.1. Error Return Codes .........................................6
5.2. Dual IPv4/IPv6 Client Considerations .......................6
5.3. Adding A and/or AAAA RRs to DNS ............................7
5.3.1. Initial DHCID RR Request ............................7
5.3.2. DNS UPDATE When FQDN in Use .........................7
5.3.3. FQDN in Use by Another Client .......................8
5.4. Adding PTR RR Entries to DNS ...............................8
5.5. Removing Entries from DNS ..................................9
5.6. Updating Other RRs ........................................10
6. Security Considerations ........................................10
7. Acknowledgements ...............................................11
8. References .....................................................11
8.1. Normative References ......................................11
8.2. Informative References ....................................11
Stapp & Volz Standards Track [Page 2]RFC 4703 Resolution of FQDN Conflicts October 20061. Introduction
"The Client FQDN Option" [8] includes a description of the operation
of [4] clients and servers that use the DHCPv4 client FQDN option.
"The DHCPv6 Client FQDN Option" [9] includes a description of the
operation of [5] clients and servers that use the DHCPv6 client FQDN
option. Through the use of the client FQDN option, DHCP clients and
servers can negotiate the client's FQDN and the allocation of
responsibility for updating the DHCP client's A and/or AAAA RRs.
This document identifies situations in which conflicts in the use of
FQDNs may arise among DHCP clients and servers, and it describes a
strategy for the use of the DHCID DNS resource record [2] in
resolving those conflicts.
In any case, whether a site permits all, some, or no DHCP servers and
clients to perform DNS updates ([3], [10]) into the zones that it
controls is entirely a matter of local administrative policy. This
document does not require any specific administrative policy, and
does not propose one. The range of possible policies is very broad,
from sites where only the DHCP servers have been given credentials
that the DNS servers will accept, to sites where each individual DHCP
client has been configured with credentials that allow the client to
modify its own FQDN. Compliant implementations MAY support some or
all of these possibilities. Furthermore, this specification applies
only to DHCP client and server processes; it does not apply to other
processes that initiate DNS updates.
2. Terminology